|Publication number||US6073181 A|
|Application number||US 08/868,348|
|Publication date||6 Jun 2000|
|Filing date||3 Jun 1997|
|Priority date||3 Jun 1997|
|Publication number||08868348, 868348, US 6073181 A, US 6073181A, US-A-6073181, US6073181 A, US6073181A|
|Inventors||William G. Holland, Joseph Franklin Logan, Joseph Gerald McDonald, Gregory Francis Paussa|
|Original Assignee||International Business Machines Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (22), Non-Patent Citations (2), Referenced by (13), Classifications (16), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Local Area Network (LAN) adapters are commonly used to attach computer systems to networks such as Ethernet, Token-Ring and FDDI. Most high performance LAN adapters operate as bus master devices on industry standard buses such as ISA, EISA, Micro Channel and PCI. As bus masters, they obtain ownership of the host computer system bus and directly transfer frames in and out of buffers located in main memory using a Direct Memory Access (DMA) process. Device driver software running in the host computer monitors and controls operation of the LAN adapter. A typical system configuration is illustrated in FIG. 1.
The device driver provides an interface between the LAN adapter and other software (hereafter application software) executing in the host computer system. The device driver interacts with the LAN adapter hardware by processing hardware interrupts, reading and writing adapter registers and servicing transmit and receive queues. The device driver interacts with the application software by servicing requests to transmit data onto the network and by forwarding data received from the network to the application software.
The vast majority of LAN adapter device driver software conform to either the Open Data-Link Interface (ODI) specification or the Network Driver Interface Specification (NDIS).
ODI and NDIS define the programming interface between the device driver and the application software. ODI was developed by Novell and is used in Novell's NetWare products, while NDIS was developed by 3 COM and Microsoft and is used in Windows operating systems. In general, bus master LAN adapters copy frames received from the LAN into a chain or linked list of buffers, allocated by the device driver, and resident in the host processor's main memory.
NDIS does not place a limitation on the number of buffers used to store a received frame, and when a received frame exceeds the storage capacity of a buffer, the excess is stored in one or more additional buffers as required and the device driver forwards the frame to the application software. On the other hand, the ODI device driver will not forward any frame which is greater than a single allocated buffer. Frames which exceed the capacity of a single buffer are discarded by the device driver as invalid.
Normally, ODI device drivers will allocate buffers having sufficient capacity to hold the largest frame that it expects to receive. This is determined by negotiation at the time the communication is established. However, under some circumstances (such as operating in a PC DOS environment) buffer sizes somewhat smaller than the maximum size supported by the LAN are selected. In those instances, it is necessary that the device driver perform an explicit check of every received frame to ensure that the buffer contains a complete frame. Otherwise, the device driver could forward a partial frame to the application software. Even though the check rarely fails, it must be done and has an adverse impact on the LAN adapter's performance by lengthening a critical device driver code path.
An object of the invention is to provide a LAN adapter which will work with device drivers conforming to both the ODI and the NDIS specifications and which will relieve the ODI device driver from the need to check each buffer for receipt of a complete frame.
Another object of the invention is to provide a LAN adapter which will provide with the receipt of each frame, status including an indicia for indicating when a received frame occupies more than a single buffer.
The invention contemplates a LAN adapter for use with LAN drivers following either the ODI or the NDIS specification resident in a host computer and a method for transferring data frames into data buffers controlled by LAN drivers following either the ODI or NDIS specification.
The method is particularly useful in a system including an adapter for receiving data frames received from a Local Area Network (LAN), a system bus connecting the adapter to a memory which includes a plurality of data buffers under control of LAN driver software located in a system main processor and comprises the following steps:
1. receiving the data encoded in frames from said LAN and transferring the received data to a predetermined buffer via the system bus,
2. accumulating the frame length and providing an output indicative of the accumulated frame length when the data frame ends,
3. comparing the output indicative of the received frame length to the size of the predetermined buffer, and
4. sending a status message to the LAN driver via the system bus indicating good status when the comparison indicates that the length of the frame did not exceed the capacity of the predetermined buffer.
FIG. 1 is a block diagram of a typical system environment in which the invention is used.
FIG. 2 is a detailed block diagram of a system including a LAN adapter constructed according to the invention.
FIG. 3 is a flowchart illustrating the operation of the LAN adapter as it implements the invention.
In FIG. 1, a host computer system includes a main processor 10 connected directly to a main memory 11 and to a LAN adapter 12 by a host bridge 14 and a system bus 15.
A more detailed view of this host system is illustrated in FIG. 2. Software 16 resident in the main processor includes an operating system, a BIOS, one or more user applications and one or more peripheral device drivers. The LAN adapter 12 includes receive data logic 20, which receives data from the LAN network 21. The received data is stored in receive buffers via bus interface 22, which transfers the received data across the system bus 15 and the host bridge 14 into one or more buffers in memory 11 which have been allocated by the LAN device driver software running in the main processor.
Receive data logic 20 maintains and updates a receive frame length counter 23. This counter is reset each time a frame starts and is incremented as each data element is received. The count is stopped at the end of the frame and applied to one input of a comparator circuit 24. Receive data logic 20 performs many other well known functions which are not relevant to this invention and will not be described herein.
Receive buffer logic is responsible for managing the buffers allocated by the LAN adapter driver software. It supplies the current buffer length 26 to the other input of comparator 24. Comparator 24 compares the buffer length provided by the receive data logic 20 at the end of a frame to the buffer length provided by the receive buffer logic 25. If the receive frame length exceeds the current buffer length, the comparator 24 provides a first output to receive buffer logic 25 indicating a potential error condition. If the receive frame length is equal to or less than the current buffer length the comparator 24 provides a second output indicating no potential error condition.
Receive buffer logic 25 also receives the output of a configuration register 27. If the ODI mode is not set, receive buffer logic 25 treats both the first and second outputs from comparator 24 only as an end of frame indicator and sends end of frame status to the LAN adapter device driver. However, if the ODI mode is indicated by the state of the configuration register, different status information is sent by the receive buffer logic 25 to the LAN adapter device driver running in the main processor. If the first output is received, error status is sent. If the second output is received, good frame received status is sent. As pointed out above, other conventional functions not described herein may effect the status, and the described status only reflects the impact on the subject matter of this invention.
The LAN adapter 12 can be implemented in hardware, programmed microprocessor or a combination of both. Each has unique advantages and disadvantages. A hardware implementation would provide speed advantage while a programmed micro processor would afford a greater degree of flexibility in design and accommodating future changes in function. However, the logical functions are substantially identical and the flow diagram illustrated in FIG. 3 is applicable to any implementation.
In FIG. 3 detection of start of frame 30 starts the transfer of received data to the designated buffer in main memory via the DMA process. At the same time, the adapter accumulates the received frame length 31. Until the end of frame is detected 32, the process defined in 31 continues.
Upon detection of the end of frame, the configuration register is checked 33. If the mode is not ODI, the LAN adapter sends good status 34 (along with other status related to other parameters) to the LAN device driver software resident in the main processor and goes to Start.
If the configuration register when checked (33) indicates that the mode is ODI, then the accumulated buffer length is compared to the assigned buffer length 35. If the frame length in not greater than the assigned buffer length, the LAN adapter goes to 34 and sends good status as described above.
If the comparison (35) indicates that the length of the received frame was greater than the capacity of the assigned buffer then it will send bad status to the LAN device driver software resident in the main processor or as an alternative will reuse the buffers and send no status to the LAN driver software 36. Each of the options has its own advantages and disadvantages.
If bad status is sent to the LAN driver, the adapter will use the next available free buffer in the list for storing the next frame received and the LAN device driver will have to manage the control of the list. If the adapter sends no status and reuses the buffers by over writing the prior frame data with new frame data, the LAN driver software is relieved of the buffer management task, however the adapter assumes additional functions related to buffer management. In the case where the buffers are reused by the adapter, no status (of any kind) is sent to the LAN device driver since the driver has no function to perform and the data stored in the buffers will be replaced by data from subsequently received frames.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US4516201 *||9 Oct 1980||7 May 1985||Burroughs Corporation||Multiplexed data communications using a queue in a controller|
|US4771391 *||21 Jul 1986||13 Sep 1988||International Business Machines Corporation||Adaptive packet length traffic control in a local area network|
|US4773043 *||6 Feb 1985||20 Sep 1988||The United States Of America As Represented By The Secretary Of The Air Force||ADCCP communication processor|
|US4881167 *||2 Mar 1989||14 Nov 1989||Hitachi, Ltd.||Data memory system|
|US5247626 *||29 May 1990||21 Sep 1993||Advanced Micro Devices, Inc.||Fddi controller having flexible buffer management|
|US5289469 *||16 Jan 1992||22 Feb 1994||Kabushiki Kaisha Toshiba||Communication control unit with lower layer protocol control and higher layer protocol control|
|US5289470 *||14 Dec 1992||22 Feb 1994||International Business Machines Corp.||Flexible scheme for buffer space allocation in networking devices|
|US5321819 *||4 May 1993||14 Jun 1994||Texas Instruments Incorporated||Interface for coupling a host device having a network interface to a computer network having a predetermined communications medium and a predetermined communications physical layer|
|US5367643 *||6 Feb 1991||22 Nov 1994||International Business Machines Corporation||Generic high bandwidth adapter having data packet memory configured in three level hierarchy for temporary storage of variable length data packets|
|US5400326 *||22 Dec 1993||21 Mar 1995||International Business Machines Corporation||Network bridge|
|US5410650 *||27 Sep 1991||25 Apr 1995||Fujitsu Limited||Message control system for data communication system|
|US5412782 *||2 Jul 1992||2 May 1995||3Com Corporation||Programmed I/O ethernet adapter with early interrupts for accelerating data transfer|
|US5422628 *||2 Dec 1993||6 Jun 1995||Rodgers; Nicholas A.||Reed switch actuated circuit|
|US5440690 *||8 Apr 1994||8 Aug 1995||Digital Equipment Corporation||Network adapter for interrupting host computer system in the event the host device driver is in both transmit and receive sleep states|
|US5442631 *||4 Mar 1994||15 Aug 1995||Kabushiki Kaisha Toshiba||Communication control device|
|US5448565 *||12 Nov 1992||5 Sep 1995||International Business Machines Corp.||Multiport LAN bridge|
|US5488724 *||15 May 1992||30 Jan 1996||Advanced Micro Devices, Inc.||Network controller with memory request and acknowledgement signals and a network adapter therewith|
|US5524007 *||13 Dec 1993||4 Jun 1996||Motorola, Inc.||Network interface architecture for a packet switch communication system|
|US5537417 *||29 Jan 1993||16 Jul 1996||International Business Machines Corporation||Kernel socket structure for concurrent multiple protocol access|
|US5541922 *||1 Oct 1993||30 Jul 1996||Nokia Telecommunications Oy||Method for assigning priority to traffic between local area networks interconnected via a backbone network|
|US5577211 *||11 May 1994||19 Nov 1996||Ibm Corporation||System and method using chained structure queues for ordering of message delivery between connected nodes wherein unsuccessful message portion is skipped and retried|
|US5729681 *||10 Oct 1995||17 Mar 1998||Intel Corporation||Method of communicating data from a host to a network controller|
|1||"Dictionary of PC Hardware and Data Communications Terms", Accessed from http://www.oreilly.com/reference/dictionary, 1996.|
|2||*||Dictionary of PC Hardware and Data Communications Terms , Accessed from http://www.oreilly.com/reference/dictionary, 1996.|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7895462||19 Mar 2008||22 Feb 2011||International Business Machines Corporation||Managing recovery and control of a communications link via out-of-band signaling|
|US7949721||25 Feb 2008||24 May 2011||International Business Machines Corporation||Subnet management discovery of point-to-point network topologies|
|US7962564||25 Feb 2008||14 Jun 2011||International Business Machines Corporation||Discovery of a virtual topology in a multi-tasking multi-processor environment|
|US8009589||25 Feb 2008||30 Aug 2011||International Business Machines Corporation||Subnet management in virtual host channel adapter topologies|
|US8015258 *||30 Sep 2002||6 Sep 2011||Zarlink Semiconductor (U.S.), Inc.||Method and apparatus for accessing variable sized blocks of data|
|US8065279||25 Feb 2008||22 Nov 2011||International Business Machines Corporation||Performance neutral heartbeat for a multi-tasking multi-processor environment|
|US8225280||28 Mar 2008||17 Jul 2012||International Business Machines Corporation||Incorporating state machine controls into existing non-state machine environments|
|US8429662||28 Mar 2008||23 Apr 2013||International Business Machines Corporation||Passing initiative in a multitasking multiprocessor environment|
|US8432793||19 Mar 2008||30 Apr 2013||International Business Machines Corporation||Managing recovery of a link via loss of link|
|US8762125||25 Feb 2008||24 Jun 2014||International Business Machines Corporation||Emulated multi-tasking multi-processor channels implementing standard network protocols|
|US8793699||19 Mar 2008||29 Jul 2014||International Business Machines Corporation||Negating initiative for select entries from a shared, strictly FIFO initiative queue|
|US20060004904 *||30 Jun 2004||5 Jan 2006||Intel Corporation||Method, system, and program for managing transmit throughput for a network controller|
|US20090257448 *||17 Jun 2009||15 Oct 2009||Internet Broadcasting Corporation||Layered multicast and fair bandwidth allocation and packet prioritization|
|U.S. Classification||709/250, 710/52, 370/463, 709/236|
|International Classification||H04L12/56, G06F11/14|
|Cooperative Classification||H04L49/9084, H04L49/9078, H04L49/9026, H04L49/9021, H04L49/90|
|European Classification||H04L49/90, H04L49/90E, H04L49/90Q3, H04L49/90R, H04L49/90G|
|3 Jun 1997||AS||Assignment|
Owner name: IBM CORPORATION, NEW YORK
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HOLLAND, WILLIAM G.;LOGAN, JOSEPH FRANKLIN;MCDONALD, JOSEPH GERALD;AND OTHERS;REEL/FRAME:008591/0702
Effective date: 19970602
|7 Jun 2004||LAPS||Lapse for failure to pay maintenance fees|
|3 Aug 2004||FP||Expired due to failure to pay maintenance fee|
Effective date: 20040606